Line data    Source code

       1             : /****************************************************************************
       2             : **
       3             : ** Copyright (C) 2016 The Qt Company Ltd.
       4             : ** Contact: https://www.qt.io/licensing/
       5             : **
       6             : ** This file is part of the QtCore module of the Qt Toolkit.
       7             : **
       8             : ** $QT_BEGIN_LICENSE:LGPL$
       9             : ** Commercial License Usage
      10             : ** Licensees holding valid commercial Qt licenses may use this file in
      11             : ** accordance with the commercial license agreement provided with the
      12             : ** Software or, alternatively, in accordance with the terms contained in
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      15             : ** information use the contact form at https://www.qt.io/contact-us.
      16             : **
      17             : ** GNU Lesser General Public License Usage
      18             : ** Alternatively, this file may be used under the terms of the GNU Lesser
      19             : ** General Public License version 3 as published by the Free Software
      20             : ** Foundation and appearing in the file LICENSE.LGPL3 included in the
      21             : ** packaging of this file. Please review the following information to
      22             : ** ensure the GNU Lesser General Public License version 3 requirements
      23             : ** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
      24             : **
      25             : ** GNU General Public License Usage
      26             : ** Alternatively, this file may be used under the terms of the GNU
      27             : ** General Public License version 2.0 or (at your option) the GNU General
      28             : ** Public license version 3 or any later version approved by the KDE Free
      29             : ** Qt Foundation. The licenses are as published by the Free Software
      30             : ** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
      31             : ** included in the packaging of this file. Please review the following
      32             : ** information to ensure the GNU General Public License requirements will
      33             : ** be met: https://www.gnu.org/licenses/gpl-2.0.html and
      34             : ** https://www.gnu.org/licenses/gpl-3.0.html.
      35             : **
      36             : ** $QT_END_LICENSE$
      37             : **
      38             : ****************************************************************************/
      39             : 
      40             : #ifndef QREFCOUNT_H
      41             : #define QREFCOUNT_H
      42             : 
      43             : #include <QtCore/qatomic.h>
      44             : 
      45             : QT_BEGIN_NAMESPACE
      46             : 
      47             : 
      48             : namespace QtPrivate
      49             : {
      50             : 
      51             : class RefCount
      52             : {
      53             : public:
      54        5801 :     inline bool ref() Q_DECL_NOTHROW {
      55        5801 :         int count = atomic.load();
      56             : #if !defined(QT_NO_UNSHARABLE_CONTAINERS)
      57        5801 :         if (count == 0) // !isSharable
      58           0 :             return false;
      59             : #endif
      60        5801 :         if (count != -1) // !isStatic
      61        5747 :             atomic.ref();
      62        5801 :         return true;
      63             :     }
      64             : 
      65       12737 :     inline bool deref() Q_DECL_NOTHROW {
      66       12737 :         int count = atomic.load();
      67             : #if !defined(QT_NO_UNSHARABLE_CONTAINERS)
      68       12737 :         if (count == 0) // !isSharable
      69           0 :             return false;
      70             : #endif
      71       12737 :         if (count == -1) // isStatic
      72        2401 :             return true;
      73       10336 :         return atomic.deref();
      74             :     }
      75             : 
      76             : #if !defined(QT_NO_UNSHARABLE_CONTAINERS)
      77             :     bool setSharable(bool sharable) Q_DECL_NOTHROW
      78             :     {
      79             :         Q_ASSERT(!isShared());
      80             :         if (sharable)
      81             :             return atomic.testAndSetRelaxed(0, 1);
      82             :         else
      83             :             return atomic.testAndSetRelaxed(1, 0);
      84             :     }
      85             : 
      86           4 :     bool isSharable() const Q_DECL_NOTHROW
      87             :     {
      88             :         // Sharable === Shared ownership.
      89           4 :         return atomic.load() != 0;
      90             :     }
      91             : #endif
      92             : 
      93         216 :     bool isStatic() const Q_DECL_NOTHROW
      94             :     {
      95             :         // Persistent object, never deleted
      96         216 :         return atomic.load() == -1;
      97             :     }
      98             : 
      99        5862 :     bool isShared() const Q_DECL_NOTHROW
     100             :     {
     101        5862 :         int count = atomic.load();
     102        5862 :         return (count != 1) && (count != 0);
     103             :     }
     104             : 
     105             :     void initializeOwned() Q_DECL_NOTHROW { atomic.store(1); }
     106             :     void initializeUnsharable() Q_DECL_NOTHROW { atomic.store(0); }
     107             : 
     108             :     QBasicAtomicInt atomic;
     109             : };
     110             : 
     111             : }
     112             : 
     113             : #define Q_REFCOUNT_INITIALIZE_STATIC { Q_BASIC_ATOMIC_INITIALIZER(-1) }
     114             : 
     115             : QT_END_NAMESPACE
     116             : 
     117             : #endif